Creux du Van in La Grande-Béroche

You're standing on the rim of the Creux du Van, a huge rocky bowl in the Swiss Jura. Go ahead and peek over the edge, but stay behind the wall. The cliffs drop around a hundred and sixty metres straight down, and they curve right around the valley like the stands of a giant amphitheatre. Altogether that wall of rock runs for about four kilometres, and it's well over a kilometre from one side to the other.